There are many situations in which it is desirable to dispense small controlled amounts of fluid in a specific location. One example is the dispensing of an adhesive in an automated production line, such as dispensing a fraction of a milliliter of UV-cured adhesive at the base of the needle of a hypodermic assembly where the adhesive is cured so as to hold the needle in place in the plastic base. There are myriad other situations in which small controlled amounts of fluid need to be dispensed very exactly.
In a production environment it is desirable to have as few interruptions as possible to an automated assembly line. One interruption occurs when a fluid dispenser needs to be refilled or replaced; the line must be halted, the fluid dispenser removed, and a full dispenser placed properly into position. Many assembly lines uses several fluid dispensers, each of which needs to hold fluid. This situation leads to the need to stop production fairly frequently so as to replace empty fluid dispensers. It is thus desirable to design the fluid dispensing system in a manner that allows the fluid dispensers to be replaced as quickly as possible.
Adhesives are dispensed from syringes in various industrial operations. It is desirable to pre-fill syringes with a known volume of fluid at a production location separate from the fluid dispensing operation. This way as syringes are emptied in the fluid dispensing operation, they can quickly and easily be replaced with properly filled syringes. Also, when multiple dispense guns are used in one system and all of the syringes are prefilled with the same amount of fluid, they all run out of fluid at the same time; this keeps reloading down time to one machine stop. This is possible due to the stepper motor and all syringes being filled to the exact same height (volume). The result is less production down time and less waste of fluid due to syringes not being completely emptied.